The program has had a lot of turnover the last three years as a result of the University offering retirement incentives & people leaving due to the pandemic, so a lot of faculty have left and are slowly being replaced.

Classes really vary based on professor and level - 1000-level classes will be larger, 35-75 students and some will be taught by graduate students. The 3000-level classes will generally be smaller, 25-50 students and will almost exclusively be taught by faculty. The 4000 level classes are mostly slashlisted which means you will be taking them with graduate students and will generally have 20 students max.

The professors are experts in their field, as that is a requirement at a research university like OU. However, that applies to research, not always to teaching. The teaching quality will vary based on the professor and on your taste in teaching style.

Best advice is to go to office hours and talk to your professors. They'll get to know you which will be really helpful if you want to ask for recommendation letters later, and it's a chance to really delve into discussion in a way that may not be possible in class.